Domain phases in antiferromagnetically coupled sandwiches

Abstract

The impact of buffer stacks containing Cr/Fe sandwiches on the quality of the antiferromagnetic coupling in Co(1.2 nm)/Cu(0.83 nm)/Co(1.2 nm) sputtered trilayers has been investigated. Coupling strengths J larger than 0.4 erg/cm2 have been realized. The completeness of the antiferromagnetic alignment of both Co layers at zero field has been probed with the soft magnetic layer in the buffer stack. No remanence could be detected, demonstrating the completeness of the AF coupling across the sandwiches. The lack in remanence is partly due to the (111) texture imposed by the buffer and polycrystallinity of the Co layers, causing low rotational friction. The freedom in the sense of rotation of the Co layers causes a dense domain configuration with domain walls having their magnetization in the centers parallel to the original saturation field Hs. This causes an increment in the magnetization component in the direction of Hs and a reduction in the resistance. The state of high domain density converts into a low density one by annihilation of domains at positive field, so that no remanence due to these domains is detected.